As is known in the art, there are a variety of rotational sensors for determining angular position. In one type of sensor, Hall effect modules are used to generate sine and cosine signals from which angular position can be determined. Such sensors use digital processing to process the sine and cosine signals generated from the Hall cells. Due to analog to digital signal conversion and other factors, such digital processing imposes limitations on the speed and accuracy of angular position determination.
For example, part number AS5043 from Austria Microsystems is an angular position sensor that digitally processes information from a Hall array using a coordinate rotational digital computer (CORDIC) that implements an iterative calculation for complex math with a lookup table. Other sensors use similar digital processing to implement various processing algorithms for computing position information.
As is known in the art, the quadrature relationship between the sinusoids used to determine angular position is important for minimizing error. The quadrature relationship is also required to find the amplitude of the sinusoidal signals using the A2 sin2 θ+A2 cos2 θ=A2 trigonometric identity, where A is the amplitude. One known approach for generating the necessary sine and cosine signals is to rotate a bipolar disc magnet above two mechanically offset magnetic sensors. However, intentional or unintentional mechanical misalignment between the magnet and sensors can cause the input sinusoids to have an arbitrary phase relationship rather than the ideal quadrature of sine and cosine.